1. Field
The present disclosure relates to a capacitive touch sensor, and a display device including the same.
2. Description of the Related Art
Recently, a digitizer, a touch screen, and the like capable of replacing an existing input device, such as a keyboard and a mouse, by directly detecting a contact position of a hand of a person or an object have been widely utilized in devices.
These devices include a touch sensor for detecting a touch position. For example, a capacitive touch sensor, a resistive touch sensor, and an optical touch sensor may be used.
Among them, the capacitive touch sensor is capable of recognizing a touch position by detecting a point at which capacitance is changed by the contact of a hand of a person or an object. Some capacitive touch sensors that are able to detect multi-touch input and have high accuracy are being recently and widely used.
Referring to FIG. 1, the capacitive touch sensor may include driving electrodes 1 for receiving driving signals Vd1 to Vd4 and sensing electrodes 2 crossing the driving electrodes 1 to output detection signals Vout.
Recently, a driving method in which the driving signals Vd1 to Vd4 are simultaneously supplied to the driving electrodes 1 utilizing an orthogonal code (for example, a Walsh-Hadamard code), as illustrated in FIG. 2, has been suggested. Using this driving method, the detection signals Vout output from the respective detection electrodes 20 may have values corresponding to a sum of the driving signals Vd1 to Vd4. Accordingly, when there is no touch event, the detection signals Vout may be output in the form illustrated in FIG. 3.
However, as FIG. 3 shows for the method in the related art, the detection signals Vout for an initial period (0 to T) have values (V1 and −V1) unlike the other periods (a sum of the driving signals Vd1 to Vd4 is 0 during the remaining periods so that a predetermined minimum value is maintained). Because the detection signals Vout for the initial period (0 to T) have the values (V1 and −V1) in the initial period, the detection signals Vout may not be readily useable for detecting a touch event.
Accordingly, to use the detection signals Vout for the initial period (0 to T), an additional circuit may be separately provided to remove the values (V1 and −V1).